any of a large group subphylum of mostly aquatic arthropods, including the lobsters, crabs, and woodlice, with a carapace, a pair of appendages on each segment, and two pairs of antennae: subphylum Crustacea
crustacean adj
crustaceous /-shəs/ adj
[Latin group name, neuter pl of crustaceus, from crusta rind, shell, crust1]